---
title: "Version 1.3.11"
description: "Enhanced error handling, authorization features, and critical bug fixes"
icon: "key"
og:image: "/images/Release1.3.11.png"
---

<Card img="/images/Release1.3.11.png" title="Release 1.3.11" href="https://github.com/mcp-use/mcp-use/releases/tag/1.3.11">
  This release brings significant improvements to MCP-Use with enhanced error handling, new authorization capabilities, and several critical bug fixes. The most notable additions include a comprehensive authorization system and improved reliability across HTTP connectors and subprocess management.
</Card>

## New Features

### Authorization System
**[PR #149](https://github.com/pietrozullo/mcp-use/pull/149) by @pietrozullo**

A comprehensive OAuth2 and Bearer token authentication framework has been added to MCP-Use, enabling secure access control for MCP servers and clients. The system includes automatic OAuth discovery, dynamic client registration, and secure token storage. Key features include file-based token storage, automatic token refresh, OAuth metadata discovery, and secure callback handling for the authorization code flow.

For detailed usage examples and configuration options, see the [Authentication documentation](/python/client/authentication).

## Bug Fixes & Improvements

### HTTP Connector Error Handling
**[PR #279](https://github.com/pietrozullo/mcp-use/pull/279) by @renvins**

Significantly improved error handling in HTTP connectors with better authentication error detection and graceful fallback between transport methods. The system now properly handles HTTP 401/403/407 errors and provides clearer diagnostic messages when authentication fails.

### Empty Tool Result Handling
**[PR #273](https://github.com/pietrozullo/mcp-use/pull/273) by @renvins**

Fixed a critical issue where empty tool results (`content: []`) were causing validation errors in the LangChain adapter. The system now correctly processes empty results and handles cases where tools legitimately return no content.

### JSON Schema Enum Validation
**[PR #270](https://github.com/pietrozullo/mcp-use/pull/270) by @Amrithesh-Kakkoth**

Resolved a validation issue in `jsonschema_to_pydantic` conversion where enum fields without explicit type declarations were failing validation. The fix automatically adds `"type": "string"` to enum fields, ensuring proper Pydantic model generation.

```python
# Before: This would fail validation
{"enum": ["x", "y", "z"]}

# After: Automatically fixed to
{"type": "string", "enum": ["x", "y", "z"]}
```

### Documentation Fix
**[PR #266](https://github.com/pietrozullo/mcp-use/pull/266) by @renvins**

Corrected a typo in the README documentation where `astream` was incorrectly referenced instead of `stream`, improving clarity for developers following the streaming examples.

### MCPAgent Execution Tracking
**[PR #254](https://github.com/pietrozullo/mcp-use/pull/254) by @hetsaraiya**

Enhanced the MCPAgent execution flow with comprehensive success/failure tracking and telemetry collection. The system now properly tracks execution status, steps taken, tools used, and execution time for better observability and debugging.

```python
# New telemetry tracking includes:
# - Execution success/failure status
# - Number of steps taken
# - Tools used during execution
# - Response time and error details
# - Agent configuration metadata
```

### Subprocess Cleanup
**[PR #231](https://github.com/pietrozullo/mcp-use/pull/231) by @lorenss-m**

Fixed a critical resource leak in subprocess management when running multiple MCP clients concurrently. The fix ensures proper process termination and cleanup, preventing zombie processes and memory leaks in long-running applications.

## Maintenance

### Automated Dependency Updates
**[PRs #261](https://github.com/pietrozullo/mcp-use/pull/261), [#253](https://github.com/pietrozullo/mcp-use/pull/253), [#248](https://github.com/pietrozullo/mcp-use/pull/248) by @github-actions[bot]**

Regular automated updates to dependent package information, ensuring the project stays current with its ecosystem and maintains compatibility with the latest versions of dependencies.
